The problem may be your AC adapter, you mention that it is not the same brand as the laptop. The AC adapter may not be able to fully charge the batteries or the problem could be in the system board. The bottom cover may have information about the AC adapter, compare that with the power information on the AC adapter. If the power needed by the laptop is greater than the input then the AC adapter should be replaced.
If you can get into the diagnostics, you can see if the AC adapter and the battery work together. If not, let your battery power drain to about 10% and plug in the AC adapter and see how long it takes to charge to 90% and then how long it takes to get to 100%.